The field of this invention is that of interconnection systems for semiconductor components and integrated circuit devices. The invention relates more particularly to interconnecting ceramic chip-carrier types of integrated circuit devices and direct-mounted integrated circuits with wire-bonded interconnects and the like in such a way as to permit high-density mounting of the devices on a low cost substrate while avoiding the interconnection-bond integrity problems and heat-dissipation problems usually associated with interconnection of such devices.
At the present time, most integrated circuit devices are provided in the form of dual-in-line packages (DIP) which are mounted and electrically interconnected on conventional glass-epoxy printed circuit (p.c.) boards and the like by having device terminals fitted onto plated-through holes in the boards, with or without the use of intermediate mounting sockets. The present invention does not exclude systems incorporating such dual-in-line packages but, with the trend toward increasingly larger numbers of pin-outs, higher speeds, and higher density of i.c. devices, it is found that much larger p.c. board areas are needed to accomodate the devices even when multilayer boards are used. Greater difficulties are encountered in trying to mount larger i.c. devices using DIP packages without damage to device terminals, and the ratio of packaging and mounting cost to i.c. device cost is becoming excessive. As a result, various different types of device packages and/or direct device attachment are being considered for facilitating interconnection at the "board" system level, commonly called the #2 level. For example, leadless ceramic chip-carriers and directly attached i.c. devices and the like have been proposed for permitting higher device mounting density in an interconnection system. However, because of the difference in thermal expansion properties between the ceramic i.c. packages or i.c. devices and the conventional p.c. boards, some compliant lead structure has typically been required between the terminals on the packages or i.c. devices and the circuit paths on the boards to assure suitable interconnection bond integrity. Some of the more recently proposed i.c. devices such as tape-automated-bonded (TAB) devices have been provided with a compliant lead structure but it is then found that the heat-dissipating properties of the conventional low cost p.c. boards are still too limited for permitting any suitable degree of device mounting density. Substrates having ceramic bases and having metal conductors deposited on top of such bases have also been proposed for use for direct i.c. chip or bar attachment or for mounting of ceramic chip carriers but the use of such known ceramic substrates has been limited by cost and fabrication technology and has typically been limited in size to less than about 100 square inches. It would be desirable if an improved electronic interconnection system could be provided for directly attaching i.c. chip or bars or for mounting ceramic i.c. devices as well as other devices of different types in an economical and convenient manner, particularly using substrate means of substantial area greater than about 100 square inches. Such a system should be adapted to provide high device density on a low cost, large scale substrate and the substrate should have heat-dissipating and thermal expansion properties which are compatible with the devices mounted in the system.